Support for await and async

The description from MDN:

The await operator is used to wait for a [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) and get its fulfillment value. It can only be used inside an [async function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/async_function) or at the top level of a [module](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules).

Await is useful for calling and waiting for results from remote services and code readability.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/await#top_level_await